package com.lnwazg.kit.swing.verifycode;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 验证码工具
 * @author nan.li
 * @version 2018年9月12日
 */
public class VerifyCodeUtil
{
    private static Color getRandColor(int fc, int bc)
    {// 给定范围获得随机颜色
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
    
    /**
     * 绘制验证码
     * @author nan.li
     * @param request
     * @param response
     * @throws IOException
     */
    public static void drawVerifyCode(HttpServletRequest request, HttpServletResponse response)
        throws IOException
    {
        // 在内存中创建图象
        int width = 60, height = 20;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        
        // 获取图形上下文
        Graphics g = image.getGraphics();
        
        // 生成随机类
        Random random = new Random();
        
        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        
        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        
        // 画边框
        // g.setColor(new Color());
        // g.drawRect(0,0,width-1,height-1);
        
        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 100; i++)
        {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }
        
        // 取随机产生的认证码(4位数字)
        String sRand = "";
        for (int i = 0; i < 4; i++)
        {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand, 13 * i + 6, 16);
        }
        
        // 将认证码存入SESSION
        request.getSession().setAttribute("verifyCode", sRand);
        // 图象生效
        g.dispose();
        
        // 输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());
    }
    
}
